1. Field of the Invention
This invention relates to a system for detecting malfunction of a transmission of a vehicle, more particularly a system for detecting failure of a shift lever position sensor that detects the shift lever position of an automatic transmission of a vehicle.
2. Description of the Prior Art
In the case of an automatic transmission shift lever having the positions P, R, N, D4, D3, 2, (1), for example, the shift lever position sensor has a fixed contact for each position and the lever has a movable contact that makes contact with the fixed contact at the position where the lever is set, causing an electric signal of a first level to be output. Positions other than the one at which the lever is set output electric signals of a second level. The position to which the shift lever is shifted can therefore be detected from the fact that only one of the plurality of positions outputs a first-level signal while the other positions output second-level signals.
With this arrangement, failure of the sensor may cause simultaneous detection of two positions or failure to detect even one position.
The object of this invention is therefore to deal with the latter case by providing a system for detecting malfunction of a transmission of a vehicle, more particularly a system for detecting failure of a shift lever position sensor for a vehicle automatic transmission, which can reliably detect failure of the shift lever position sensor to detect even one position.